In recent days, a wide variety of electronic devices including smart phones have been spread due to the advancement of information communication technology. A variety of applications including photo-taking and text-messaging are embedded in the smart phones.
Generally, the screen lock or lock screen function is employed in smart phones. The screen lock refers to a state wherein a smart phone displays only certain information while disabling most of the other smart phone functions, at the time of initial booting of the smart phone, after a certain time elapses without use of the smart phone, or upon user request.
The screen lock function restricts phone calls and prevents the leakage of private information, such as the contents of photo-transmission or text messaging.
Methods for releasing a screen lock use numbers or preset touch patterns as a password. Screen lock releasing methods run the risk of password leakage to those who are near to the phone user, due to the repeated input of the same numbers or touch patterns and thus, are greatly vulnerable to the leakage of private information of the user.